Answer:
peptide antigens by MHC class II molecules
Explanation:
Helper T cells are activated by peptide antigens by MHC class II molecules. These antigens express on the surface of antigen-presenting cells (APCs). After activation, the T helper cells divide and secrete cytokines to assist the immune response.
If you are implying one these choices not needed for survival it would be parents only when you can survive on your own (I'm not that sure but I hope this helped the slightest but)
Coughing can be a symptom along with shortness of breath
The seven units that form the basis for all derived units in the metric system are called the base units. Math: Powers of ten. Language: Prefixes. Kilograms: another kind of measurement. Hope this helped :)
